Paddy Soil

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Under Paddy Soils refers to anthropogenic embossed / formed soils under wet rice cultivation. According to the WRB, an anthraquic horizon with an underlying hydragric horizon is characteristic .

Classification in the classification systems

Paddy Soil is a slang term. The WRB refers to them as Hydragric Anthrosols . In the US Soil Taxonomy , classification as Agrudalf or Plaggept is possible.

The German Soil Science Society (DBG) has no name for Paddy Soils, as these cannot be found in Germany. A designation as “anthropogenic-hydromorphous Kultosol” would be possible.

nomenclature

The word paddy soil is derived from the Indonesian word 'padi', which means rice. Paddy Soil therefore refers to rice soils. However, the term is only used for well-developed wet rice soils. The word rice soils is by no means synonymous, as it is an umbrella term for soils under rice cultivation in general.

distribution

Since paddy soils are always closely linked to wet rice cultivation and wet rice cultivation without paddy soil underneath is only possible in very young rice fields (under 20 years of age), the spread of paddy soils can be equated with that of wet rice cultivation. Spread of rice cultivation see separate article rice .

genesis

General development process

The original rock and soil type are of minor importance for the formation of a paddy soil . Typically they are Ferric Acrisols. These are extremely unsuitable for other arable farming and can almost exclusively be used for wet rice cultivation.

First, the field is placed under water retention. Then processed by so-called "wet plowing". This corresponds to normal plowing, with the difference that the soil is strongly compacted when plowing under water. The resulting plow sole is one of the characteristic horizons of paddy soil.

A homogeneously mixed anaerobic topsoil forms over the plow sole. This represents the root space for the rice plant and is also characteristic.

An aerobic layer about 10 millimeters thick forms above the anaerobic horizon, which usually has a greatly increased concentration of blue-green algae.

Under the plow, the soil (subsoil horizon) remains largely aerobic. It is also characteristic of Paddy Soil.

The characteristic soil horizons

Anthraquic Horizon: ( Anthr- as an indication of anthropogenic influence, -aquic as an indication of water stagnation ) This consists of the "Puddled Layer" and the "Plow Pan". The “puddled layer”, an intensively and homogeneously mixed topsoil horizon, has both reduced and oxidized areas. The reduced ones clearly predominate. For the "Plow Pan", see the plow sole already described above.

Hydragic Horizon: ( Hydr- again as an indication of the influence of water and -agric as an indication of agricultural use) Sub- soil horizon with predominantly oxidising areas and partly iron and manganese concretions.

Processes, Properties and Fertility

Oxygen loss

In the Anthraquic Horizon, most of the oxygen supply is used up during the growing season. Since the rice plant not only tolerates this, but can actively compensate for it, this is not to be assessed negatively for the fertility of the rice soil.

Fe and Mn mobilization

The reductive conditions ensure an intensive reduction of the iron and manganese oxides, which are mobilized in the soil solution and consequently made available to plants. As long as the iron concentrations do not reach toxicity , this can be assessed as positive.

Denitrification

The anaerobic conditions of wet rice cultivation ensure the agronomically undesirable process of denitrification. See separate article Denitrification .

Ecosystem problems

See separate article rice (wet rice cultivation).

swell

  • BGR, FAO (2007): World Reference Base for Soil Resources 2006. Hannover, 128 pp.
  • EITEL, B. (2001): Soil geography. In: the Geographical Seminar [ed. DUTTMANN et al] Braunschweig, 244 pp.
  • GLASER, B. (2006): Anthrosols. Soil Physics Department, Bayreuth University. 44 pp.
  • KYUMA, K. (2004): PADDY SOIL SCIENCE. KYOTO, 280 pp.
  • SIEGMUND, J. (2010): Terra Preta and Paddy Soil. Anthropogenic soils of the tropics. Augsburg, 14 pp.
  • USDA (1999): Soil Taxonomy. Second Edition, Washington, 871 pp.